Java Security

Hello,

I used RSA algorithm for encryption and i can send the encrypted text to the server , on the server side
in order to decrypt the message i passed the public key, but how to generate the private key on the server side, i am a beginner in cryptography, can anybody help me , if possible give me the coding for encryption and decryption which will work on the client side for encryption and server side for decryption,i need RSA algorithm for it